Damage to primary visual cortex early in life results in a massive reorganization within the brain. The cortico-cortical projections within the cortex reorganize the lateral geniculate nucleus of the thalamus degenerates and 90% of 2 ganglion cells in the retina die. These changes take place quickly because if the lesion takes place one month later, there is less reorganization in the cortex and LGN and the retinal ganglion cells survive. The purpose of this proposal is to test whether removing a select population of ganglion cells at a vulnerable stage in development will impact the survival of presynaptic cells. We propose to take a simple approach: remove a single type of ganglion cell during a critical stage in development, count the various cell classes that are present and screen for specific bipolar and amacrine cell types with commercially available markers. Our preliminary results suggest that transneuronal retrograde degeneration of 2 ganglion cells after early lesions of primary visual cortex alters the composition of the INL in a cell-specific way. This approach is unique because we are eliminating a single population of ganglion cell without knocking out regulatory genes or physically manipulating the retina to see whether specific presynaptic cells are directly impacted by death of their targets. This research is important because it may reveal the retinal circuits that are most affected following damage to visual cortex as well as ones that could be exploited in people suffering from visual deficits due to brain trauma or neurodegenerative disease. Public Health Relevance: The purpose of this proposal is to investigate whether damage to visual cortex and subsequent loss of retinal ganglion cells from the retina induces reorganization of the inner nuclear layer in the retina. This research is important because it may reveal the retinal circuits that are most affected following damage to visual cortex as well as ones that could be exploited in people suffering from visual deficits due to brain trauma or neurodegenerative disease.